The first two above were published a few days before the first state seceded.
At this point, the newspapers were in a bit of a panic about the revenue.
The last article was written a day after secession. It is good to note that nowhere does it complain of slavery as either a problem or cause of of secession....unlike many here who would minimize the financial panic by presenting slavery hyperbole.
After just a couple of weeks, the editorials became more aggressive as seen in these:
“It is the enforcement of the revenue laws, not the coercion of the State that is the question of the hour. If those laws cannot be enforced, the Union is clearly gone; if they can, it is safe”
~Philadelphia Press, January 15, 1861
“They [the South] know that it is their import trade that draws from the people's pockets sixty or seventy millions of dollars per annum, in the shape of duties, to be expended mainly in the North, and in the protection and encouragement of Northern interest.... These are the reasons why these people do not wish the South to secede from the Union. They [the North] are enraged at the prospect of being despoiled of the rich feast upon which they have so long fed and fattened, and which they were just getting ready to enjoy with still greater gout and gusto. They are as mad as hornets because the prize slips them just as they are ready to grasp it.”
~New Orleans Daily Crescent, January 21, 1861
“The Southern Confederacy will not employ our ships or buy our goods. What is our shipping without it? Literally nothing. The transportation of cotton and its fabrics employs more ships than all other trade. It is very clear that the South gains by this process, and we lose. No-we MUST NOT let the South go!”
~Union Democrat (Manchester, New Hampshire), February 19, 1861
Interestingly, still no talk of slavery.....only MONEY.
When the only tool you have is a hammer, you try to make all your problems look like nails.
They couldn't tell the truth; That they wanted the South to keep paying a disproportionate share of the bills; That they wanted to keep making those millions of dollars from the labor of slaves;
The truth wouldn't work, because regardless of what the businessmen and the governing rulers were, the ordinary people were quite moral and they would not be induced to attack others simply because they were losing jobs and trade to them.
No, the ordinary public had to be induced into this, and the truth would not motivate them to war.
Thus the hyperbole and propaganda.
First, I can't find evidence that any of those quotes are valid.
Second, even if we pretend they are legit, slavery in the South was a major concern for only a small number of Northern abolitionists.
But slavery was the important reason cited by secessionists for their declarations and that's why so many Northerners, especially Democrats, were perfectly happy to propose giving secessionists whatever constitutional concessions they might wish on slavery.